use std::{env, error::Error, fs};
pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    let contents = fs::read_to_string(config.filename)?;

    let results = if config.case_sensitive {
        search(&config.query, &contents)
    } else {
        search_case_insensitive(&config.query, &contents)
    };

    for line in results {
        println!("{}", line);
    }

    Ok(())
}

pub struct Config<'a> {
    pub query: &'a String,
    pub filename: &'a String,
    pub case_sensitive: bool,
}

impl<'a> Config<'a> {
    pub fn new(args: &'a [std::string::String]) -> Result<Config<'a>, &'static str> {
        if args.len() < 3 {
            return Err("not enough arguments");
        }
        let query = &args[1];
        let filename = &args[2];
        let case_sensitive = env::var("CASE_INSENSITIVE").is_err();
        Ok(Config {
            query,
            filename,
            case_sensitive: case_sensitive,
        })
    }
}

pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    contents
        .lines()
        .filter(|line| line.contains(query))
        .collect()
}

pub fn search_case_insensitive<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    let query = query.to_lowercase();
    let mut results = Vec::new();

    for line in contents.lines() {
        if line.to_lowercase().contains(&query) {
            results.push(line);
        }
    }

    results
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_run() -> Result<(), String> {
        if let Err(e) = run(Config {
            query: &String::from("searchstring"),
            filename: &String::from("poem.txt"),
            case_sensitive: env::var("CASE_INSENSITIVE").is_err(),
        }) {
            return Err(e.to_string());
        } else {
            Ok(())
        }
    }

    #[test]
    fn test_config() -> Result<(), String> {
        let args: [String; 3] = [
            String::from(""),
            String::from("searchstring"),
            String::from("poem.txt"),
        ];
        if let Err(e) = Config::new(&args) {
            return Err(e.to_string());
        };
        Ok(())
    }
    #[test]
    fn case_sensitive() {
        let query = "duct";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.";

        assert_eq!(vec!["safe, fast, productive."], search(query, contents));
    }
    #[test]
    fn case_insensitive() {
        let query = "rUsT";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.
Trust me.";
        assert_eq!(
            vec!["Rust:", "Trust me."],
            search_case_insensitive(query, contents)
        );
    }
}
